function disponibles_init(field, params) {
    $("[name='data[Inventario]["+params.listen+"]']").change(function() {
        field.empty().append('<option value=""></option>');
        if (empty(this.value)) {
            return;
        }
        $.ajax({
            type: 'GET',
            url: WWW + 'stocks/disponibles/' + this.value,
            success: function(data) {
                var jdata = $.parseJSON(data);
                for (var i in jdata) {
                    var stock = jdata[i].Stock;
                    field.append('<option value="'+stock.id+'">'+stock.producto+' ('+stock.cantidad+')</option>');
                }
            }
        });
    });
}